The present invention relates to apparatus for centering and rotatably supporting elongated solid or tubular bar stock as well as to apparatus for feeding such bar stock into a machine tool or lathe.
Bar stock support devices have been generally used for supporting a length of bar stock adjacent a machine tool during machining operations. When the bar stock is to be turned in a lathe, means must be provided for rotatably supporting the bar stock as it is being machined. One type of conventional bar stock supporting apparatus includes one or more elongated support tubes which receive and rotatably support the bar stock. Pressurized oil is directed into the space between the bar stock and the inner wall of the support tube, usually in a swirling manner, for lubricating the bar stock as it is rotated at high speed by the lathe.
To accommodate bar stock of different diameters, elongated support tubes of correspondingly different diameters are necessary in the above-described apparatus. This, of course, adds to the overall cost of the apparatus by requiring multiple support tubes and further makes it very cumbersome and expensive to stock enough support tubes to optimally support a wide variety of sizes of bar stock. Certain alternatives have been proposed in the past which include the utilization of replaceable, semicylindrical spacers inside either a plurality of semicylindrical supports or inside a longitudinally split tube. For example, the use of a plurality of semicylindrical supports and inner, replaceable support bushings is illustrated in Arisaka et al. U.S. Pat. No. 4,995,298. Such devices, however, still result in lost production time consumed by installation and adjustment procedures and further result in additional costs due to the manufacture and stocking of a multiplicity of spacers of varying size.
Ramunas U.S. Pat. No. 4,289,051 discloses an apparatus for lifting and centering bar stock so that the bar stock is on the centerline of an adjacent machine tool spindle regardless of the diameter of the bar stock and regardless of the distance which the bar stock is to be lifted. While the apparatus of Ramunas does not require the use of multiple spacers to accommodate bar stock of varying diameter, it has certain other disadvantages. For example, the Ramunas device is a relatively complex and therefore expensive apparatus. Moreover, the Ramunas device is not designed for use with a lathe which rotates the bar stock. Instead, it is designed only to move or translate the bar stock axially into a multispindle machine tool which performs multiple machining operations on the nonrotating piece of bar stock.
Certain other problems exist with prior bar stock supporting and/or feeding apparatus including the problems and hazards associated with loading the bar stock into the apparatus and unloading the bar stock from the apparatus. In the past, these operations have generally required that the operator's hands be placed dangerously close to moving parts of the apparatus. One device for automatically loading bar stock into a feeding mechanism is shown in Hartle U.S. Pat. No. 3,447,694. The device disclosed by Hartle makes use of a generally L-shaped mechanism for loading bar stock into a feed apparatus. One of the drawbacks of the Hartle device, however, is that it provides no mechanism for unloading the bar stock from the feed apparatus and thus, if an operator desires to unload the bar stock from the feed apparatus, the operator's hands must be placed into the feed apparatus therefore risking injury. Ramunas U.S. Pat. No. 4,289,051 also discloses a bar stock loading mechanism but, like Hartle, fails to provide any means for safely unloading the bar stock from the feed apparatus.